1. Field of the Invention
The present invention relates to an electrophotographic photosensitive member, a method of manufacturing the electrophotographic photosensitive member, and a process cartridge and an electrophotographic apparatus each having the electrophotographic photosensitive member.
2. Description of the Related Art
Electrophotographic photosensitive members with organic photoconductive substances (organic electrophotographic photosensitive members) have been intensively studied and developed in recent years.
The electrophotographic photosensitive member basically includes a support and a photosensitive layer formed on the substrate. In the case of the organic electrophotographic photosensitive member, a photosensitive layer is prepared using a charge-generating substance and a charge-transporting substance as photoconductive substances and a resin for binding these substances (binder resin).
There are two types of layer structure of the photosensitive layer: a multilayer type and a monolayer type. In the multilayer type, the function of charge generation and the function of charge transfer are assigned (functionally separated) respectively to a charge-generating layer and a charge-transporting layer. In contrast, in the monolayer type, both the function of charge generation and the function of charge transfer are assigned to one layer.
Most of electrophotographic photosensitive members employ multilayer type photosensitive layers. In many cases, charge-transporting layers are provided as the surface layers of the electrophotographic photosensitive members. In addition, for enhancing the durability of the surface of an electrophotographic photosensitive member, a protective layer may be provided as the surface layer of the electrophotographic photosensitive member.
The surface layer of the electrophotographic photosensitive member requires various types of properties. Among the various properties, wear resistance is particularly important because the surface layer is brought into contact with various types of members and paper sheets.
In many cases, various types of measures have been taken to the surface layers of electrophotographic photosensitive members to improve the wear resistance of the electrophotographic photosensitive members. For improving the wear resistance by providing the surface with low friction, for example, Japanese Patent Application Laid-Open No. H06-332219 (Patent Document 1) discloses the technology of including (dispersing) fluorine-atom-containing resin particles made of, for example, a tetrafluoroethylene resin into the surface layers of the particles.
At the time of dispersing the fluorine-atom-containing resin particles, a method of using a dispersing agent for increasing dispersibility has been known (see, for example, Patent Document 1). In the case of using the dispersing agent to disperse the fluorine-atom-containing resin particles, the dispersing agent requires a surface-activating function (function of dispersing the fluorine-atom-containing resin particles so that the particles are provided with fine particle sizes). It has been conventionally desired to satisfy both of the surface-activating function and the property of being inactive to electrophotographic properties (property of not obstructing charge transfer), and thus various studies have been conducted.